The present invention is directed to an improvement in an optical cable having a plurality of optical transmission element, each element having at least one optical fiber, and a plurality of auxiliary elements for supporting tension loads, said transmission elements being stranded with the auxiliary elements on a central core with an alternating direction of twist and the stranded elements being covered by a common surrounding jacket.
An optical cable, which includes both optical transmission elements and auxiliary elements that are stranded with an alternating twist on a cable is disclosed in German O.S. No. 27 09 106. In the cable of this patent, the optical transmission elements are stranded onto a central core with an alternating direction of twist so that the direction of twist is retained for a maximum of approximately two lengths of lay. The optical transmission elements themselves are loosely disposed or, respectively, disposed so as to be displaceable in the circumferential direction of the core. This is achieved by utilizing auxiliary elements, which are designed as stiffening elements or skeins and are present for mechanical reasons such as supporting tension loads and are firmly pressed against the core by means of a jacket which are applied on the outside of the cable. These auxilliary events with the core and the jacket form circumferential spaced channels that have an alternating twist and each channel loosely receives a plurality of transmission elements.
It is desirable in some instances to have a large reserve length for the optical transmission element which can be exploited when needed. This can be in the case for instance when the optical cable has already been installed and is damaged at a specific location. Thus, it needs to be repaired by means of utilizing a repair socket. In this case, a sufficient amount of excess length for the optical transmission elements must be available. However, it is not admissable to exert to great a mechanical longitudinal stress on the optical transmission element in order to achieve this excess length.